Technology called MEMS (Micro Electro Mechanical System), which realizes functions of an electronic device on a micro IC chip, has been progressing remarkably in recent years. MEMS makes it possible to realize sensor chips having measurement and wireless communication functions. Measurements produced by such sensor chips can be collected by wireless communication. Such sensor chips can, therefore, be installed arbitrarily in diversified locations. They are expected to find applications where equipment management or environmental management is required to be more meticulous than before.
When using such small wireless sensors, it becomes necessary to have a means for knowing where they are installed. To grasp where sensor chips are installed, it used to be necessary to note down locations where sensors are installed on a drawing on paper while identifying types of sensor chips installed by sensor installation personnel and subsequently register information grasped in such a way in a geographical information system (GIS). Even under such a circumstance, sensor installation personnel may be able to access the GIS via a network, but it is still necessary to associate, at where the sensor chips are installed, sensor information with location information. Such work is quite troublesome when the number of sensor chips involved is very large.
To simplify the work, a positioning function such as GPS may be incorporated in each sensor chip, so that the location of the sensor chip can be automatically registered when it is installed. Incorporating a positioning function in a sensor chip, however, makes the sensor chip larger in size and more complicated in configuration. A technique for grasping locations of objects without a positioning function is disclosed, for example, in Japanese Patent Laid-Open No. H11(1999)-259569. When the technique is applied to a merchandise information management system having a map interface, location information associated with merchandise information transmitted from a mobile terminal can be easily registered in a merchandise information providing server.